Can't help you with a failed throttle body (mine's fine - touch wood!)
but the usual cause of problems is the butterfly needing cleaning, gunk
and carbon tends to build up around the circumference of the butterfly
causing it to stick.

Give it a good clean with carburettor cleaner and see if that cures your
problems.  If cleaning doesn't improve things then the potentiometers
could be failing There are a pair, one on the throttle pedal side of the
system and the other on the ECU motor driven side, when the resistance's
get out of step  the ECU complains, trips the TB to limp home and you
get a check engine light) this due to the same gunk that coats the
butterfly leaking out of seals, I'm not aware if these are easily
replaced (or even if you can get them as separate parts), I've not heard
of anyone doing anything other than putting a new TB on in this
situation.

I've lifted this text from a thread on Saabscene that explains how it
works.

http://www.saabscene.com/forum/index.php?showtopic=31612443

'When you accelerate/decelerate the potentiometer in the TB varies a
voltage to the ECU (related to how much you have put your foot down or
lifted it up). The ECU (Trionic) uses this info, along with load
requirements, various temperatures, airflow, rpm, etc. to send a signal
back to the TB which drives the electric motor round to the desired
position. It is the motor that moves the butterfly not the throttle
cable in normal operation. The ECU is clever enough to also work out the
rate of putting your foot down and can change the mixture ratio when it
senses harder acceleration. Related to the rate of change of the
potentiometer. The old carburettor equivalent was the diaphragm pump
that used to squirt in some neat petrol when hard acceleration was
required. It's my own personal belief that a dirty throttle body doesn't
respond quickly enough to get the acceleration mixture right and hence
some misfire which disappears if you ease off. Seems very sensitive but
then this system is supposed to be.'

and this also

http://www.saabscene.com/forum/index.php?showtopic=348700

'On the side of the throttle body there is a black unit with a 10pin
connector. The unit has a throttle sensor and a pedal position sensor
built in ( Backup )Both of these sensors have to add up to 5v. So,if
sensor 1 is 3.1 and sensor 2 is 2.0 a difference of 0.1v is recognised
so on comes the "check engine" light and limp home is activated. Causing
the revs to drop and more pressure on the gas to pull away.'

Cheers,

Andy